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J Am Acad Audiol 3: 221-224 (1992)
Relationship of Pure-Tone Averages to Speech
Reception Threshold for Male and Female
Speakers
John P. Preece*
Cynthia G. Fowler*
Abstract
The availability of a compact disc with a female speaker for clinical use has raised the issue
of the equivalence between the female speaker and the previous standard male speaker for
assessing the speech reception threshold (SRT) . This study evaluated the relationship of
two- and three-frequency averages to the SRT for a male speaker on an audio tape and a
female speaker on a compact disc in two similar groups of clinic patients, each consisting of
215 ears . There were no significant differences between the SRTs for the two groups,
suggesting that the two speakers/recordings are equivalent for clinical purposes. The SRTs
from both speakers/recordings were within 6 dB of both the two- and three-frequency
averages . There were no significant differences between the SRTs and the three-frequency
average.
Key Words: Spondee, detection threshold, SRT
he relation between the pure-tone
threshold and the speech reception
T threshold (SRT) has been of interest to
audiologists for some time (Hughson and
Thompson, 1942 ; Carhart, 1971). The SRT, assessed with spondaic words, generally agrees
well with the average of the pure-tone thresholds for 500, 1000, and 2000 Hz (Carhart, 1946)
or the lowest two thresholds of those three (Fletcher, 1950). The relation between the SRT and
the two- or three- frequency pure-tone average
is most frequently used as an indication of reliability of the pure-tone average (Olsen and
Matkin, 1991) .
Kruel et al (1969) noted that recordings of
a word list made by different speakers should be
considered as independent tests and standardized individually . Recently, the Department of
Veterans Affairs (VA) produced an audio compact disc (CD) for auditory assessment (Wilson
and Preece, 1990). Included on the disc are lists
of spondees produced by a female speaker. The
CD has been distributed to all VA audiology
clinics and is available to all other clinics. The
material on the CD was intended to replace the
audio tapes of a male speaker that were provided by Auditec of St . Louis. A previous study
of young listeners with normal hearing found
no significant difference in detection or recognition functions for male or female speakers
(Cambron et a1,1991) . The purpose ofthe present
study was to determine if there was a difference
in the SRT or in the relation of the SRT to the
pure-tone average for the old recording (male
speaker, audio tape) and the new recording
(female speaker, CD) for a large group of clinic
patients, representing a wide age range and a
variety of hearing impairments . The VA Compensation and Pension (C & P) evaluation procedures, which are rigidly standardized, offered
a particularly stable sample for assessment of
the new spondee recording.
METHOD
*University of California, Irvine, and VA Medical Center,
Long Beach, California
Reprint requests : John P . Preece, Audiology-126, VA
Medical Center, 5901 East Seventh Street, Long Beach, CA
90822
he subjects were veterans reporting to the
TAudiology Clinic at the Department of Veterans Affairs Medical Center, Long Beach, for C
& P evaluations . The OLD group consisted of
221
Journal of the American Academy of Audiology/Volume 3, Number 3, May 1992
veterans who reported for C & Pin the 6 months
prior to the installation of the CD players. This
group listened to spondaic words (CID W-1)
from a male speaker recorded on audio tape .
Taped materials were played on either reel-toreel decks (Revox B-77) or on cassette decks
(Nakamichi MR-2). The NEW group consisted
of an equal number of ears of veterans who
reported for C & Pin a 6-month period following
the installation of compact disc players in all of
the clinic test suites . This group listened to
spondaic words (CID W-1) from a female speaker
recorded on a compact disc . Compact disc materials were played on either Sharp DXR 840 or
Yamaha CDX 510U players.
The two ears of each subject were considered independently (Phillips et al, 1990). Any
ear that included thresholds above the test limits (105 dB HL for tones or speech) was eliminated from the present study, as were results
from any test session with other than "good"
reliability . These requirements resulted in 215
ears in each group. No specific matching of
subjects was performed other than the limits as
noted above. The mean age for the OLD group
was 46 .8 years (SD 15 .8, range 21 to 89) and the
mean age for the NEWgroup was 45 .4 years (SD
14 .2, range 21 to 80). Subjects were not selected
for configuration or type of hearing loss . The
distribution of subjects by gender and by type of
hearing loss is shown in Table 1. In this table,
"within normal limits" refers to the standards
set in VA Central Office (1982) and only considers thresholds from 500 to 4000 Hz .
All tests were performed in double-walled
sound suites (IAC, Model 1204A) under earphones (TDH 50P or equivalent in MX-41/AR
cushions) . The audiometers were either GS1704 or GSI-10s . In all cases, the equipment
Table 1 Description of Subjects Forming the
OLD Group (Male Speaker, Audio Tape) and
NEW Group (Female Speaker, CD)*
OLD Group
Gender
Males
Females
Age (years)
Mean
Range
Hearing
Within normal limits
Sensorineural
Conductive
Mixed
NEW Group
106
4
468
101
6
45 .4
21-89
21-80
83
118
94
108
9
5
*Hearing categories include all ears tested .
2
11
was calibrated acoustically quarterly (ANSI,
1989) and biologic listening checks were performed daily.
All audiometric procedures were performed
as outlined in the VA professional services memorandum (VA Central Office, 1982). For the
SRT, the patients were first familiarized with
the words face-to-face and were required to repeat the words to the audiologist . The SRT protocol used an ascending procedure from 0 dB HL,
with presentation of one word at each 10-dB increment until the veteran responded correctly.
The intensity was then decreased by 15 dB, and
eight words were presented at each level ascending in 2-dB steps until at least four words
were repeated correctly. The lowest level at
which four words were repeated correctly was
identified as the SRT. Pure-tone thresholds
were assessed using an ascending technique
beginning at 0 dB HL . Masking was used whenever appropriate for pure tones and for speech .
RESULTS AND DISCUSSION
igure 1 presents a long-term spectral analyFsis of the two sets of speech materials
recorded on a spectrum analyzer (Briiel and
Kjaer, Type 2033) . Each plot represents the
average of 256 samples taken at random intervals from the spoken words . Amplitude has
been normalized for this figure . The top panel
shows the spectrum of the male speaker/audio
tape, the middle panel shows the spectrum of
the female speaker/CD, and the bottom panel
shows the difference between the two waveforms. For both speakers there is a major lowfrequency peak with very little energy above
5000 Hz . The major difference between the two
spectra is between 2500 and 5000 Hz where the
NEW recording has a 10-20 dB higher amplitude .
Figure 2 contains bivariate plots of the
individual data points for the OLD group (upper
panels) and the NEW group (lower panels), with
the SRT on the abscissa and the two-frequency
averages on the left two ordinates and the
three-frequency averages on the right two ordinates . The diagonal lines through each panel
represent linear regressions on the data . The
slopes of the regression lines are all very close
to unity and vary from 0 .92 (OLD, two-frequency average) to 1 .07 (NEW, three-frequency
average) . The r2 values are all greater than 0.93,
reflecting excellent modeling of the data . The
SRT, therefore, increases linearly with both the
two- and three-frequency pure-tone averages .
222
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SRT and Pure-Tone Thresholds/Preece and Fowler
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100
2
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OLD
+
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3-FA
+
+
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+
+
+ +
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20
00
-60
a
+
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40
-40
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2-FA
60
-20
m
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a0
60
+
100
NEW
2-FA
80
-80
I
0
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i
NEW
3-FA
.,.
+
r
40
20
-20
0
-20
-40
0
20
40
60
60
100
0
20
40
60
60
100
SPEECH RECEPTION THRESHOLD (dB HL)
Figure 2 Bivariate plots of the individual data points
for the OLD group (upper panels) and the NEW group
(lower panels), with the SRT on the abscissa and the twofrequency average on the left two ordinates and the threefrequency averages on the right two ordinates . The diagonallines through each panel represent linear regressions
on the data .
- 60
gw - 80
I
40
i
i-I-I
I
I
20
0
-20
-40
0
2000
4000
6000
8000
10000
FREQUENCY (Hz)
Figure l Long-term spectral analysis of the two sets of
speech materials. The top panel shows the spectrum ofthe
male speaker, the middle panel shows the spectrum of the
female speaker, and the bottom panel shows the difference between the two waveforms (female-male).
Table 2 presents the means, standard deviations, and ranges for the two-frequency and
three-frequency pure-tone averages, and for the
SRT for the two speakers/recordings in the two
subject groups . The three-frequency average is
the mean of the thresholds for 500, 1000, and
2000 Hz, and the two-frequency average is the
mean ofthe best (lowest) two thresholds for 500,
1000, or 2000 Hz . The agreement of the SRT
with the two- and three-frequency averages
within both groups is well within the generally
accepted 6-dB guideline (Carhart, 1971 ; Olsen
and Matkin, 1991). Within the groups, the twofrequency and three-frequency pure-tone averages and the SRT are highly correlated, ranging
from 0.940 to 0.984, as expected (Table 3) .
In order to determine the significance of the
differences between speakers/recordings for the
pure-tone averages or for the SRT, a two-way
analysis of variance (ANOVA) with repeated
measures was performed.* There were no significant differences between the pooled thresholds for the OLD and NEW groups or for the
interaction between subject groups and type of
threshold test . There was, however, a significant difference (F[2,8561 =135 .95, p < .O1) in the
thresholds depending on the type of test (puretone averages versus SRT) . Post hoc comparisons of individual test means, using pairedsample t-tests,* revealed no significant difference between the SRT scores for the two subject
groups . This lack of significance indicates that
the two recordings for the SRT are equivalent in
clinical use . This conclusion supports the prediction of equivalence by Cambron et al (1991)
based on functions for young, normal hearing
subjects .
The differences between SRTs and two- or
three-frequency averages were the same for
both speaker/recordings . For the subject groups
pooled, the paired t-tests demonstrated a significant difference (t[429] = 18 .6, p < .01) between the two-frequency and three-frequency
pure-tone averages . This difference is expected
Table 2 Means and Standard Deviations in
dB HL for the OLD and NEW Groups*
OLD group
Range
NEW group
Range
2-FA
3-FA
SRT
16 .1 (19 .0)
-7 to 95
18 .1 (19 .9)
-10 to 95
19 .5 (20 .3)
-5 to 98
21 .5(20-9)
-5 to 98
19 .7 (20 .0)
-5 to 95
22 .4 (19 .1)
0 to 100
*2-FA is the two-frequency average, 3-FA is the
three-frequency average, and SRT is the speech
reception threshold .
*Northwest Analytical (1986) . Statpak, v. 4 .1 . Portland,
Oregon : Northwest Analytical, Inc
223
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y nKS-+
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Journal of the American Academy of Audiology/Volume 3, Number 3, May 1992
Table 3 Correlations between Variables for
the OLD Group and NEW Group*
Corre lation
2-Frequency Average
2-Frequency Average
3-Frequency Average
3-Frequency
average
SRT
SRT
OLD
NEW
984
984
969
965
948
940
*All correlations were statistically significant
(p < 0 .01) .
because the subject groups included approximately 50 percent of ears with sensorineural
hearing losses, many of which had high frequency hearing losses . In these cases the twofrequency average is expected to be lower than
the three-frequency average. Contrary to previous literature (Fletcher,1950), the two-frequency
average was significantly (t[429] = 14.5, p < .01)
lower than the SRT. This discrepancy, which
was equal for the two groups (3 .6 dB for the OLD
group and 4.3 dB for the NEW group), may be
related to phonemic regression in some of the
oldest patients (Gaeth, 1948) in the present
subject sample, whose ages ranged into the 80s.
There was no significant difference between the
three-frequency pure-tone average and the SRT,
in agreement with Carhart (1946) .
(ANSI S3 .6-1989) . New York, NY : Acoustical Society of
America.
Cambron NK, Wilson RH, Shanks JE . (1991) . Spondaic
word detection and recognition functions for female and
male speakers . Ear Hear 12 :64-70 .
Carhart R. (1946) . Monitored live voice as a test of auditory acuity. JAcoust Soc Am 17 :339-349 .
Carhart R. (1971) . Observations on relations between
threshold for pure tones and for speech . J Speech Hear
Disord 36 :476-483 .
Fletcher H. (1950) . A method of calculating hearing loss
for speech from an audiogram. Acta Otolaryngol 90 :
Supp1:26-37 .
Gaeth J. (1948) . A Study of Phonemic Regression in
Relation to Hearing Loss. Doctoral dissertation, Northwestern University, Evanston, IL .
Hughson W, Thompson EA. (1942) . Correlation ofhearing
acuity for speech with discrete frequency audiograms .
Arch Otolaryngol 36 :526-540 .
Kruel EJ, Bell DW, Nixon JC . (1969) . Factors affecting
speech discrimination test difficulty . J Speech Hear Res
12 :281-287 .
Olsen WO, Matkin ND . (1991) . Speech audiometry . In :
Rintelmann WF, ed . HearingAssessment. 2nd Ed . Austin,
TX :Pro-Ed.
Phillips DS, Trune DR, Mitchell C. (1990) . Solving the
"one ear vs . two ears" data analysis dilemma. Hear J
43 :27-32.
REFERENCES
VA Central Office . (1982). Professional Services Memorandum . Audiology and Speech Pathology Service. M-2,
Part XVIII.
American National Standards Institute . (1989) . American National Standard Specification for Audiometers.
Wilson RH, Preece JP . (1990) . Development of a compact
disc for speech audiometry . Audiol Today 2:24-26 .
224
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